Cushioning device for rock drill handles



Nov. 28, 1950 J. H. ANDERSON 2,531,800

CUSHIONING DEVICE FOR ROCK DRILL HANDLES Filed Nov. 22, 1947 as 31 44 4639 3 Y W 5 4 3 i n. M

2| 42 I l L 24 24 53 |l 38 4s INVENTOR JAMES H. ANDERSON.

HIS ATTORNEY.

Patented Nov. 28, 1 950 CUSHIONING DEVICE FOR. noon DRILL HANDLES JamesH. Anderson, Easton, Pa., assignor to Ingersoll-Rand Company, New York,N. Y., a corporation of New Jersey Application November 22, 1947, SerialNo. 787,595

This invention relates to rock drills, and more particularly to acushioning device for rock drills of the manually supported type havinghandles whereby the rock drill may be held to the work.

One object of the invention is to minimize the transmission of shock andvibration from the rock drill to the handle.

A more specific object is to utilize the air compressed by the rockdrill piston in an end of the piston chamber as a medium for cushioningthe handle of the rock drill.

Other objects will be in part obvious and in part pointed outhereinafter.

In the drawings accompanying this specification and in which similarreference numerals refer to similar parts,

Figure 1 is a side elevation, partly broken away, of a rock drill havingthe invention applied thereto,

Figure 2 is an elevation taken through Figure 1 on the line 2-2,

Figure 3 is a transverse view taken through Figure 1 on the line 3-3,and

Figure 4 is a perspective view of a detail.

Referring more particularly to the drawings, the invention is shownembodied in a rock drill comprising a cylinder 2! and front and backheads 22 and 23, respectively. These parts constitute the casing of therock drill and are clamped together in assembled relationship by theusual spring-pressed side bolts 24.

Within the cylinder 2| is a piston chamber 25 having a free exhaust port26 and containing a reciprocatory hammer piston 21 that controls theexhaust port 25, and in the rearward end of the cylinder 2! is a valvechamber 28 that communicates with the rear and front ends of the pistonchamber through ports 29 and 30, respectively, and contains adistributing valve 3|, of the oscillatory plate type, for controllingthe flow of pressure fluid from the valve chamber 28 to the ends of thepiston chamber. The supply of pressure fluid for the valve chamber 28 isconveyed thereto by a passage 32 in the back head 2.3, and communicationbetween the passage 32 and the source of pressure fluid supply (notshown) is controlled by a throttle valve 33 rotatable in the back head.

The front end of the piston chamber 25 is closed by a front cylinderwasher 34, and a stem 35 on the piston extends slidably therethrough tostrike against a drill steel 36 guided by the front head 22 in a wellknown manner.

The back head 23, as is customary, supports the handle structure for therock drill and, to this 5 Claims. (Cl. 121-36) end, is provided with apair of rearwardly extending arms 31 having apertures 38, preferably ofrectangular shape, to accommodate blocks 39 that are slidable thereinendwise of the arms 31. At the outer ends of the blocks, and on theopposite sides thereof, are flanges 49 to bear against the outer sidesof the arms 31, and the inner ends of the blocks seat against the endsof a sleeve 4| that holds the blocks 39 in suitably spaced relation witheach other to determine the correct degree of clearance between theflanges 40 and the arms The blocks 39 and the sleeve 4| are apertured toaccommodate a bolt 42 that supports, on its end portions, rubber gripmembers 43 containing reinforcing sleeves 44 that seat at their innerends against the blocks 39 and at their outer ends against washers 45,one of which is interposed between the head 46 of the bolt and the gripportion and the other between the nut t! on the bolt 42 and the adjacentgrip portion 43. Owing to this arrangement, the pressure of the bolthead 46 and the nut 4'! against the outer ends of the sleeves M willpress the blocks 39 firmly. "against the ends of the sleeve 4! and thegrip members 43 will be restrained against endwise movement on the bolt.

In the form of the invention shown, the arms 3'! are so positioned thatthe longitudinal planes of the apertures 38 lie exteriorly of the planeof the cylinder 2| and on the same Side of the cylinder is anenlargement 48 which is recessed to provide a cushioning chamber 49 thatis sealed at its rearward, open end by a plug 50 having an aperture 5|to receive, slidably, a transmission member shown as being in the formof a rod 52 that extends slidably through the back head 23 and at itsrearward end into a recess 53 in the sleeve ll to abut the bolt $2.,

The opposite end of the rod 52 lies within the cushioning chamber 49 andcarries a head54 having a pressure surface 55 at its free end againstwhich cushioning fluid acts for cushioning the movement of the handlestructure longitudinally of the rock drill. The cushioning medium flowsinto the cushioning chamber 49 through a passage 56 leading thereto'fromthe forward end of the piston chamber 25 and a spring-pressed checkvalve 51 in the passage 56 prevents the return flow of fluid medium fromthe cushioning chamber to the piston chamber.

In practice, a portion of the pressure fluid initially admitted to thefront end of the piston chamber by the valve 3| for driving the piston21 rearwardly will flow through the passage 56 3 into the cushioningchamber 49 and, acting against the pressure surface, will press the rod52 against the bolt 42. Thereafter, each time the piston approaches theend of its working stroke some of the air compressed thereby will flowinto the cushioning chamber. The pressure valueflof the air. thuscompressed' is; as. is

well known, considerablyhigher than that of the fluid serving to actuatethe piston and may,

therefore, be of sufficiently high value when act-.-

ing against a small pressure surface 55. tosubstantially balance theforce applied by the opera tor to the handle for pressing the drillsteel against the work. This is highlydesirable since it obviates theneed of adding materiaily to the weight of the rock drill as would bethe case were motive fluid used as the cushioning medium.

I claim:

1. In a cushioning device for rock drills, the combination of a casing:having a piston chambei'; a.-.fiuidactuated recipro'catory piston inthepiston-chamber acting to compress fluid. insaid pistonchamber, guidemeans on the casing, a; handle for guiding the rockdrill and beingslid-v able' in theg'uide Ineansand means subjected to fluid mediumcompressed'by the piston for cushioning them'ovementof the handle.

2'. In a cushioning device for rockdrills, the.

combination of a casing having a piston chamber, afluid actuatedreciprocatory. pi tonin the piston chamber. to compre s in said.

piston chamber, guide means on the casing, av

handle forguiding the rock drill and being slidable inthe guide means, acushioning chamber in the casing, a transmission member to engage thehandle andex-tending into the cushioning ber; a pressure surface on thetransmission memher, and a passage in the casing to oonveyfiuid.

ber in the casing, a transmission member to engage the handle andextending into the cushioning chamber, a pressure surface on thetransmission member, and a passage in the casing to convey fluid mediumcompressed by the piston from the front end of the piston chamber to actagainst the pressure surface for cushioning the handle.

4. In a cushioning devic for rock drills, the combination of a casinghavin a piston chamher, a fluid actuated reciprocatory piston in thepiston chamber; a handle for guiding the rock drill and being movableendwise thereof, a cushioning; chamber; in the casing, a transmissionmember subjected to cushionin fluid within the cushioning chamberandengaging the handle for cushioning themovement of the handle, a passagein the casing to convey cushioning fiuid from the piston" chamber intothe cushioning chamher, and a check valve tcrcontrol the passage forpreventing the return flow of cushioning fluid throughthe passage,

5. In: a cushioning device for rock drills, the,

combinationof a casing having a piston chame ber, a fiuidactuatedreciprocatory piston in the piston. chamber, a handle for guiding therock, drill and being movable endwise thereof, means I on the casing forguiding the handle, an en'- largement; on the side of the casing havinga cushioning chamber, a transmission member in the cushioning chamber toengage the handle, means on the casing to guide the transmission member,a passage in the casing to convey cushioning' fluid from an. end of thepiston chamber into the-cushioning chamber, and check valve;

for preventing the return flow of cushioning fluid,

through the passage.

JAMES H. ANDERSON.

REFERENtJES CITED The following file of this patent:

UNITED STATES PATENTS references are of record in the-

